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    Subject[PATCH 5/5] KVM: selftests: Add MONITOR/MWAIT quirk test
    From
    Add a test to verify the "MONITOR/MWAIT never fault" quirk, and as a
    bonus, also verify the related "MISC_ENABLES ignores ENABLE_MWAIT" quirk.

    If the "never fault" quirk is enabled, MONITOR/MWAIT should always be
    emulated as NOPs, even if they're reported as disabled in guest CPUID.
    Use the MISC_ENABLES quirk to coerce KVM into toggling the MWAIT CPUID
    enable, as KVM now disallows manually toggling CPUID bits after running
    the vCPU.

    Signed-off-by: Sean Christopherson <seanjc@google.com>
    ---
    tools/testing/selftests/kvm/.gitignore | 1 +
    tools/testing/selftests/kvm/Makefile | 1 +
    .../selftests/kvm/x86_64/monitor_mwait_test.c | 127 ++++++++++++++++++
    3 files changed, 129 insertions(+)
    create mode 100644 tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c

    diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
    index 0ab0e255d292..1a56522f009c 100644
    --- a/tools/testing/selftests/kvm/.gitignore
    +++ b/tools/testing/selftests/kvm/.gitignore
    @@ -27,6 +27,7 @@
    /x86_64/hyperv_svm_test
    /x86_64/max_vcpuid_cap_test
    /x86_64/mmio_warning_test
    +/x86_64/monitor_mwait_test
    /x86_64/platform_info_test
    /x86_64/pmu_event_filter_test
    /x86_64/set_boot_cpu_id
    diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
    index 9a256c1f1bdf..bbbfdeb7ee9b 100644
    --- a/tools/testing/selftests/kvm/Makefile
    +++ b/tools/testing/selftests/kvm/Makefile
    @@ -56,6 +56,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/hyperv_svm_test
    TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test
    TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
    TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
    +TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test
    TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
    TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test
    TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id
    diff --git a/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
    new file mode 100644
    index 000000000000..b9af8e29721e
    --- /dev/null
    +++ b/tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c
    @@ -0,0 +1,127 @@
    +// SPDX-License-Identifier: GPL-2.0
    +#include <fcntl.h>
    +#include <stdio.h>
    +#include <stdlib.h>
    +#include <string.h>
    +#include <sys/ioctl.h>
    +
    +#include "kvm_util.h"
    +#include "processor.h"
    +
    +enum monitor_mwait_testcases {
    + MWAIT_QUIRK_DISABLED = BIT(0),
    + MISC_ENABLES_QUIRK_DISABLED = BIT(1),
    + MWAIT_DISABLED = BIT(2),
    +};
    +
    +static void guest_monitor_wait(int testcase)
    +{
    + /*
    + * If both MWAIT and its quirk are disabled, MONITOR/MWAIT should #UD,
    + * in all other scenarios KVM should emulate them as nops.
    + */
    + bool fault_wanted = (testcase & MWAIT_QUIRK_DISABLED) &&
    + (testcase & MWAIT_DISABLED);
    + u8 vector;
    +
    + GUEST_SYNC(testcase);
    +
    + vector = kvm_asm_safe("monitor");
    + if (fault_wanted)
    + GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
    + else
    + GUEST_ASSERT_2(!vector, testcase, vector);
    +
    + vector = kvm_asm_safe("monitor");
    + if (fault_wanted)
    + GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
    + else
    + GUEST_ASSERT_2(!vector, testcase, vector);
    +}
    +
    +static void guest_code(void)
    +{
    + guest_monitor_wait(MWAIT_DISABLED);
    +
    + guest_monitor_wait(MWAIT_QUIRK_DISABLED | MWAIT_DISABLED);
    +
    + guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED | MWAIT_DISABLED);
    + guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED);
    +
    + guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED | MWAIT_QUIRK_DISABLED | MWAIT_DISABLED);
    + guest_monitor_wait(MISC_ENABLES_QUIRK_DISABLED | MWAIT_QUIRK_DISABLED);
    +
    + GUEST_DONE();
    +}
    +
    +int main(int argc, char *argv[])
    +{
    + uint64_t disabled_quirks;
    + struct kvm_vcpu *vcpu;
    + struct kvm_run *run;
    + struct kvm_vm *vm;
    + struct ucall uc;
    + int testcase;
    +
    + TEST_REQUIRE(kvm_has_cap(KVM_CAP_DISABLE_QUIRKS2));
    +
    + vm = vm_create_with_one_vcpu(&vcpu, guest_code);
    + vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
    +
    + run = vcpu->run;
    +
    + vm_init_descriptor_tables(vm);
    + vcpu_init_descriptor_tables(vcpu);
    +
    + while (1) {
    + vcpu_run(vcpu);
    +
    + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
    + "Unexpected exit reason: %u (%s),\n",
    + run->exit_reason,
    + exit_reason_str(run->exit_reason));
    +
    + switch (get_ucall(vcpu, &uc)) {
    + case UCALL_SYNC:
    + testcase = uc.args[1];
    + break;
    + case UCALL_ABORT:
    + TEST_FAIL("%s at %s:%ld, testcase = %lx, vector = %ld",
    + (const char *)uc.args[0], __FILE__,
    + uc.args[1], uc.args[2], uc.args[3]);
    + goto done;
    + case UCALL_DONE:
    + goto done;
    + default:
    + TEST_FAIL("Unknown ucall %lu", uc.cmd);
    + goto done;
    + }
    +
    + disabled_quirks = 0;
    + if (testcase & MWAIT_QUIRK_DISABLED)
    + disabled_quirks |= KVM_X86_QUIRK_MWAIT_NEVER_FAULTS;
    + if (testcase & MISC_ENABLES_QUIRK_DISABLED)
    + disabled_quirks |= KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT;
    + vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, disabled_quirks);
    +
    + /*
    + * If the MISC_ENABLES quirk (KVM neglects to update CPUID to
    + * enable/disable MWAIT) is disabled, toggle the ENABLE_MWAIT
    + * bit in MISC_ENABLES accordingly. If the quirk is enabled,
    + * the only valid configuration is MWAIT disabled, as CPUID
    + * can't be manually changed after running the vCPU.
    + */
    + if (!(testcase & MISC_ENABLES_QUIRK_DISABLED)) {
    + TEST_ASSERT(testcase & MWAIT_DISABLED,
    + "Can't toggle CPUID features after running vCPU");
    + continue;
    + }
    +
    + vcpu_set_msr(vcpu, MSR_IA32_MISC_ENABLE,
    + (testcase & MWAIT_DISABLED) ? 0 : MSR_IA32_MISC_ENABLE_MWAIT);
    + }
    +
    +done:
    + kvm_vm_free(vm);
    + return 0;
    +}
    --
    2.36.1.255.ge46751e96f-goog
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